Parse XML string with LINQ, create new object from xml

Question

Given the following requirements and code, I have not yet found ONE answer that actually works.

I have an XML field in a SQL Server Database table. Why is it in there? I have no idea. I didn't put it in there. I just have to get the data out and into a List that I can combine with another List to populate a grid in a WPF app that has an MVVM architecture.
Here is that List: List QAItems = new List();

The QADailyXValueCalCheck type is as follows:

     using System.Xml.Serialization;

    namespace ConvertXmlToList {
    [XmlRoot(ElementName = "column")]
public class QADailyXValueCalCheck {
[XmlElement] 
public string Regs { get; set; }
    [XmlElement]
    public string BasisTStamp { get; set; }
    [XmlElement]
    public string DAsWriteTStamp { get; set; }
    [XmlElement]
    public string InjEndTime { get; set; }
    [XmlElement]
    public bool Manual { get; set; }
    [XmlElement]
    public decimal RefValue { get; set; }
    [XmlElement]
    public decimal MeasValue { get; set; }
    [XmlElement]
    public string Online { get; set; }
    [XmlElement]
    public decimal AllowableDrift { get; set; }
[XmlElement]
public bool FailOoc { get; set; } = false;
    [XmlElement]
    public bool FailAbove { get; set; }
    [XmlElement]
    public bool FailBelow { get; set; }
    [XmlElement]
    public bool FailOoc5Day { get; set; }
    [XmlElement]
    public decimal InstSpan { get; set; }
    [XmlElement]
    public decimal GasLevel { get; set; }
    [XmlElement]
    public string CId { get; set; }
    [XmlElement]
    public string MId { get; set; }
    [XmlElement]
    public string CylinderId { get; set; }
    [XmlElement]
    public string CylinderExpDate { get; set; }
    [XmlElement]
    public string CylinderVendorId { get; set; }
    [XmlElement]
    public string CylinderGasTypeCode { get; set; }
        }
    }

The XML is being stored in a string, xmlString and comes out of the db in the following form:

    <Regs>40CFR75</Regs>
    <BasisTStamp>2016-02-15 05:18</BasisTStamp>
    <DASWriteTStamp>2016-02-15 05:40</DASWriteTStamp>
    <InjEndTime>2016-02-15 05:23</InjEndTime>
    <Manual>0</Manual>
    <RefValue>169.7</RefValue>
    <MeasValue>169.27</MeasValue>
    <Online>14</Online>
    <AllowableDrift>15</AllowableDrift>
    <FailAbove>0</FailAbove>
    <FailBelow>0</FailBelow>
    <InstSpan>300</InstSpan>
    <GasLevel>MID</GasLevel>
    <CID>111</CID>
    <MID>N10</MID>
    <CylinderID>CC357464</CylinderID>
    <CylinderExpDate>2022-08-12</CylinderExpDate>
    <CylinderVendorID>B22014</CylinderVendorID>
    <CylinderGasTypeCode>BALN,SO2,NO,CO2</CylinderGasTypeCode>

Now, in order to get past the XML API's problem with "rootless" xml, I've added a root:

    xmlString = "<columns>" + xmlString + "</columns>";

To parse this, I use:

    XDocument doc = XDocument.Parse(xmlString);

Finally, to attempt to extract the VALUES from the XML and populate an instance of QADailyXValueCalCheck, I have the following code - which was adapted to work from other examples - THAT DO NOT WORK.

                var xfields =
            from r in doc.Elements("columns")
            select new QADailyXValueCalCheck
            {
                Regs = (string) r.Element("Regs"),
                BasisTStamp = (string) r.Element("BasisTStamp"),
                DAsWriteTStamp = (string) r.Element("DASWriteTStamp"),
                InjEndTime = (string) r.Element("InjEndTime"),
                Manual = (bool) r.Element("Manual"),
                RefValue = (decimal) r.Element("RefValue"),
                MeasValue = (decimal)r.Element("MeasValue"),
                Online = (string)r.Element("Online"),
                AllowableDrift = (decimal)r.Element("AllowableDrift"),
                //FailOoc = (bool)r.Element("FailOoc"),
                //FailAbove = (bool)r.Element("FailAbove"),
                //FailBelow = (bool)r.Element("FailBelow"),
                //FailOoc5Day = (bool)r.Element("FailOoc5Day"),
                //InstSpan = (decimal)r.Element("InstSpan"),
                //GasLevel = (decimal)r.Element("GasLevel"),
                CId = (string)r.Element("CID"),
                MId = (string)r.Element("MID"),
                CylinderId = (string)r.Element("CylinderId"),
                CylinderExpDate = (string)r.Element("CylinderExpDate"),
                CylinderVendorId = (string)r.Element("CylinderVendorId"),
                CylinderGasTypeCode = (string)r.Element("CylinderGasTypeCode")
            };

The code immediately above does NOT create a new instance of the class, "QADailyXValueCalCheck" which can be added to the List. I have a few null values that are causing a problem with that code, but that is a separate issue that I will deal with another time.

For now, can anyone tell me how that "var xfields = " query instantiates a new QADailyXValueCalCheck object that can be added to my List of the same type?

What code is missing? Thank you to the LINQ/XML genius that can answer this.

Answer 1

I had a similar question on XML parsing the other day from someone else here: Create a List from XElements Dynamically

I think in the end you would be better served using a class with xml adornments and then have extension classes that serialize or deserialize the data. This makes it better IMHO in two ways: 1. You don't have to rewrite the parser and the POCO class, just the POCO class. 2. You can be free to reuse the extension method in other places.

using System;
using System.Collections.Generic;
using System.Xml.Serialization;

namespace GenericTesting.Models
{
  [XmlRoot(ElementName = "column")]
  public class QADailyXValueCalCheck
  {
  [XmlElement]
  public string Regs { get; set; }
  [XmlElement]
  public string BasisTStamp { get; set; }
  [XmlElement]
  public string DAsWriteTStamp { get; set; }
  [XmlElement]
  public string InjEndTime { get; set; }
  [XmlElement]
  public int Manual { get; set; }
  [XmlElement]
  public decimal RefValue { get; set; }
  [XmlElement]
  public decimal MeasValue { get; set; }
  [XmlElement]
  public int Online { get; set; }
  [XmlElement]
  public decimal AllowableDrift { get; set; }
  [XmlElement]
  public bool FailOoc { get; set; } = false;
  [XmlElement]
  public int FailAbove { get; set; }
  [XmlElement]
  public int FailBelow { get; set; }
  [XmlElement]
  public bool FailOoc5Day { get; set; }
  [XmlElement]
  public decimal InstSpan { get; set; }
  [XmlElement]
  public string GasLevel { get; set; }
  [XmlElement]
  public string CId { get; set; }
  [XmlElement]
  public string MId { get; set; }
  [XmlElement]
  public string CylinderId { get; set; }
  [XmlElement]
  public string CylinderExpDate { get; set; }
  [XmlElement]
  public string CylinderVendorId { get; set; }
  [XmlElement]
  public string CylinderGasTypeCode { get; set; }
  }
}

And for the purpose of serializing/deserializing let me give extension methods for those:

using System.IO;        
using System.Xml;
using System.Xml.Serialization;

namespace GenericTesting
{                                   
  static class ExtensionHelper
  { 
    public static string SerializeToXml<T>(this T valueToSerialize)
    {
      dynamic ns = new XmlSerializerNamespaces();
      ns.Add("", "");
      StringWriter sw = new StringWriter();

      using (XmlWriter writer = XmlWriter.Create(sw, new XmlWriterSettings { OmitXmlDeclaration = true }))
      {
        dynamic xmler = new XmlSerializer(valueToSerialize.GetType());
        xmler.Serialize(writer, valueToSerialize, ns);
      }

      return sw.ToString();
    }

    public static T DeserializeXml<T>(this string xmlToDeserialize)
    {
      dynamic serializer = new XmlSerializer(typeof(T));

      using (TextReader reader = new StringReader(xmlToDeserialize))
      {
        return (T)serializer.Deserialize(reader);
      }
    }
  }
}

And a simple main entry point in a console app:

static void Main(string[] args)
{
    var thingie = new QADailyXValueCalCheck
    {
      Regs = "40CFR75",
      BasisTStamp = "2016-02-15 05:18",
      DAsWriteTStamp = "2016-02-15 05:40",
      InjEndTime = "2016-02-15 05:23",
      Manual = 0,       //Boolean This will probably mess up  Changed to Int
      RefValue = 169.7M,
      MeasValue = 169.27M,
      Online = 14,  //Mismatch Type?  Change to Int
      AllowableDrift = 15,
      FailAbove = 0,     //Boolean This will probably mess up   Changed to Int
      FailBelow = 0,     //Boolean This will probably mess up    Changed to Int
      InstSpan = 300,
      GasLevel = "MID",     //This is marked as a decimal?     Changed to string                                                
      CId = "111",             
      MId =  "N10",
      CylinderId= "CC357464",
      CylinderExpDate ="2022-08-12",
      CylinderVendorId = "B22014",
      CylinderGasTypeCode = "BALN,SO2,NO,CO2"
  };

  var serialized = thingie.SerializeToXml();

  var deserialized = serialized.DeserializeXml<QADailyXValueCalCheck>();

  Console.ReadLine();
}

This serializes just like this and I can get it back to deserialized as well.